Magnetic recording and reading device

ABSTRACT

A magnetic recording and reading device having a transfer rate of not less than 50 MB/s includes a magnetic recording medium having an absolute value of normalized noise coefficient per recording density of not more than 2.5×10 −8  (μVrms)(inch)(μm) 0.5 /(μVpp), and magnetic head which is mounted on an integrated circuit suspension so that a total inductance is reduced to be not more than 65 nH and having a magnetic core which is not more than 35 μm of length, wherein a part of the magnetic core being formed by a magnetic film having a resistivity exceeding at least 50 μΩcm or by a multilayer film consisting of a magnetic film and an insulating film. The device also includes a fast R/W-IC having a line width of not more than 0.35 μm which is installed in a position within 2 cm from a rear end of the magnetic head.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a magnetic disc device used incomputers, information storage devices and so on, a magnetic storagedevice used in such information home appliances as digital VTRs, and amagnetic recording, and and, more particularly, to a magnetic recordingand reading device suitable for realizing high-speed recording andreading, and for high-density recording.

[0002] Semiconductor memories, magnetic memories, etc., are used in thestorage or recording devices of information equipment. Semiconductormemories are used in internal primary storage in the light of high-speedaccessibility and magnetic memories are used in external secondarystorages in the light of a high capacity, low cost and nonvolatileproperty. Magnetic disk devices, magnetic tapes and magnetic cards arethe main current in magnetic memories. A magnetic recording portionwhich produces a strong magnetic field is used in order for writingmagnetic information in recording media, such as magnetic disks,magnetic tapes or magnetic cards. Further, reading portions based on themagnetoresistance effect or the electromagnetic induction effect areused in reading magnetic information recorded at a high desisty. Inrecent years, for reading, the gigant magnetoresistance effect and thetunneling magnetoresistive effect have also begun to be examined. Thesefunctional portions for recording and reading are both installed in aninput-output part which is called a magnetic head.

[0003] The basic configuration of a magnetic disk device is shown inFIGS. 10A and 10B. FIG. 10A shows a plan view of the device and FIG. 10Bshows a vertical-sectional view of the device. Recording media 101-1 to101-4 are fixed to a hub 104 to be rotated by a motor 100. In FIG. 10Bshows one example which comprises four magnetic disks 101-1 to 101-4 andeight magnetic heads 102-1 to 102-8. However, the magnetic disk devicemay comprise at least one magnetic disk and at least one magnetic head.The magnetic heads 102-1 to 102-8 move on the rotating recording media.The magnetic heads 102-1 to 102-8 are supported by a rotary actuator 103via arms 105-1 to 105-8. Suspensions 106-1 to 106-8 have function of thepressing the magnetic heads 102 against the recording media 101-1 to101-4 under a determined load, respectively. A given electric circuit isneeded for processing of reproduction signals and for inputting andoutputting of information. Recently, a signal processing circuit inwhich waveform interference at high-density is positively utilized, suchas PRML (Partial Response Maximum Likelihood) or EPRML (Extended PRML)which is an enhanced PRML, has been adopted, contributing greatly to ahigh-density design. The signal processing circuit is installed in acircuit board on a cover 108, etc.

[0004] The functional portion for writing and reading information on amagnetic head assembly is comprises components shown in FIG. 11A, forexample. A writing portion 111 is comprised of a spiral coil 116 betweenmagnetic poles 117, 118 which are magnetically connected with eachother. The magnetic poles 117, 118 are both composed of a magnetic filmpattern, which are made of an NiFe alloy, etc., respectively. Thereading portion 112 comprises a magnetoresistance element 113 made of anNiFe alloy, etc. and an electrode 119 for applying a constant current ora constant voltage to the element 113 and for detecting changes inresistance. The magnetic pole 118, which is made of an NiFe alloy, etc.and serves also as a magnetic shielding layer, is provided between thewriting and reading portions. There is further a shielding layer 115underneath the magnetoresistance element 113. A reading resolution isdetermined by the clearance distance between the shielding layer 115 andthe magnetic pole 118 (serving also as another shielding layer). Thefunctional portion is formed on a magnetic head slider 1110 (FIG. 11B)via an underlayer 114 made of Al₂O₃, etc. Incidentally, the magnetichead slider, which is provided with a protection layer made ofhard-carbon, etc. on the surface opposed to the magnetic recordingmedium, is supported by a gimbal 1111 and a suspension 1113, as shown inFIG. 11B. The magnetic head slider moves relatively to the magneticrecording medium while floating from the medium surface and, afterpositioning in an arbitrary position by an arm 1114 connected to amotor, realizes the function of writing or reading magnetic informationvia lead lines 1116 and 1115. With respect to the above function, thereis also provided an electric control circuit together with theaforementioned signal processing unit or on the head carriage.

[0005] A detailed structure of a recording medium is schematically shownin FIG. 12. As described in JP-A-3-16013, most of the conventionallyused recording media are produced by forming a magnetic layer 123 madeof a Co—Cr—Ta alloy, or a Co—Cr—Pt alloy, etc. on a non-magneticsubstrate made of Al plated with an NiP alloy, a glass, a high-hardnessceramics, a polished Si or the like, or a plastic substrate 121 by thesputtering method, or the evaporation method, or the plating method,etc. Usually, an under layer 122 made of Cr, or a Cr alloy, etc. fororientation control of the magnetic layer is often formed on thesubstrate. Furthermore, a protection film 124 made of diamond-likecarbon containing nitrogen and/or hydrogen, or SiO₂ or SiN or ZrO₂, etc.is provided to ensure durability of sliding resistance, and alubricating film 125 made of perfluoro alkyl polyether having anadsorptive or a reactive end group, or organic fatty acids, etc. isprovided.

[0006] In addition to the magnetic recording device, magneto-opticrecording devices that perform recording and reading on a magneticrecording medium through the use of light have also been put topractical use. The magneto-optic recording devices are classified intoone type in which recording is performed only by light modulation andanother type in which recording and reproduction are performed by lightwith a modulated magnetic field. However, the both types greatly rely onheat when recording and reading. Therefore, according to such type ofdevices, it is impossible to perform recording and reading in high datatransfer rate and thus they have been adopted mainly in backup systems,etc.

[0007] The importance of a storage device is determined by its storagecapacity and the speed during inputting-outputting operations. In orderto increase competitiveness of products, it is necessary for the storagedevice to increase capacity by higher recording density, higherrotational speed and higher data transfer rate than those of the priorart. Thus, an important problem to be solved by the present invention isto provide a device capable of recording and reading at a high datatransfer rate of not less than 50 MB/s and, more preferably, that at ahigh density of not less than 5 Gb/in². A magnetic recording mediumcapable of recording and reading at a high frequency and capable ofobtaining a high S/N ratio at a high density and a magnetic head capableof generating a sufficient magnetic recording field at a high frequencyare necessary for meeting the requirement.

[0008] In conventional magnetic recording media, there have beenproposed and actually carried out to reduce noise by refining crystalgrains in order to obtain a high S/N ratio at a high density of about 1to 3 Gb/in², and by promoting segregation of non-magnetic components atgrain boundaries to reduce exchange coupling among crystal grains asbeing taught in JP-A-63-148411, JP-A-3-16013 and JP-A-63-234407 so as tomake the coercive squareness S* to not more than 0.85 and the rotationalhysteresis loss RH to the range of 0.4 to 1.3. Noise can be considerablyreduced by recording and reading at a data transfer rate of not morethan about 20 MB/s. However, when the magnetic recording was carried outon that film media of the prior art at a high frequency of not less than50 MB/s, thermal fluctuation effects in fine magnetic crystallines isremarkable due to weak exchange coupling among crystal grains and theapparent coercive force is high resulting in that it was impossible torecord on it accurately. Furthermore, even when recording is performedunder a large current with utilization of a modified recording circuit,etc., the magnetic recording transition region is widened due to a broadmagnetic recording field resulting in that noise increases and/orrecorded information is lost when it was alowed to stand for a longtime.

SUMMARY OF THE INVENTION

[0009] An object of the present invention is to provide a low-noisemagnetic recording medium composed of fine crystal grains which iscapable of recording and reading at a high data transfer rate of notless than 50 MB/s and further permits high-density recording at not lessthan about 5 Gb/in², a recording and reading magnetic head with highreading sensitivity which is capable of sufficiently sharp recording onthe medium, and a magnetic recording device of a high data transfer rateand high density which is realized by using the magnetic recordingmedium and the magnetic head of the present invention.

[0010] In order to achieve the above object, the present inventorspushed forward studies on chemical compositions of magnetic recordingmedia, deposition processes and technologies related to devices such asmagnetic heads, and found out that the following means are veryeffective.

[0011] There is proposed a magnetic recording medium with a magneticlayer comprising at least one metal element selected from the groupconsisting of Co, Fe and Ni as a primary component, at least twoelements selected from a second group consisting of Cr, Mo, W, V, Nb,Ta, Ti, Zr, Hf, Pd, Pt, Rh, Ir and Si, and at least one element selectedfrom a third group consisting of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy,Ho, Er, Tm, Yb, Lu, Bi, Sb, Pb, Sn, Ge and B. According to the magneticrecording medium, it is possible to obtain a high S/N (signal-to-noise)ratio even under recording at high data transfer rate of not less than50 MB/s and to reduce the absolute value of normalized noise coefficientper a unit transition {square root}{square root over (Nd²−No²)}·{squareroot over (Tw)}/(S₀·D) (Nd: recorded media noise, No: DC erase noise,Tw: effective read track width, S₀: isolated pulse output, D: recordingdensity in the unit of flux change per inch) to not more than 2.5×10⁻⁸(μVrms) (inch)(μm)^(0.5)/(μVpp)

[0012] The invention can provide a magnetic recording device which canperform recording at a high data transfer rate of not less than 50 MB/sby using the above magnetic recording medium, a magnetic recording headand an R/W-IC having the following features; that is, the magneticrecording head assembly is given a total inductance reduced to not morethan 65 nH because it has a magnetic core length of not more than 35 μm,because it is provided with a magnetic film with a resistivity exceeding50 μΩcm or a multilayer film composed of a magnetic film and aninsulating film in part of the magnetic core, and further because it ismounted on an integrated circuit suspension; and the R/W-IC producedusing a process of a line width of not more than 0.35 μm and is capableof operating at high frequencies. Furthermore, the magnetic recordingdevice of the present invention can perform the reading of magneticinformation at a high density of not less than 5 Gb/in² by using amagnetic head provided with a read element having a giantmagnetoresistance effect or a tunneling-magnetoresistance effect andwith an effective track width of not more than 0.9 μm.

[0013] Recording density can be increased about 20% by forming themagnetic layer of the magnetic recording medium through a non-magneticintermediate layer comprising at least one element selected from thegroup consisting of Cr, Mo, W, V, Nb, Ta, Zr, Hf, Ti, Ge, Si, Co, Ni, Cand B as a primary component.

[0014] A magnetic recording and reading device of higher density can beprovided by performing magnetic recording immediately after heatapplication to a magnetic recording medium through the use of asemiconductor laser, etc. and performing reading with the aid of theabove giant magnetoresistance effect element or an element having atunneling-magnetoresistive thin film.

[0015] Furthermore, in order to shorten an access time and performpositioning with higher accuracy, it is effective to adopt a rotary typeactuator to position the head in at least two stages of coarse and finemovement adjustments.

[0016] The precent inventors pushed forward on read-and-write propertiesof a magnetic recording medium as shown in FIG. 12, which is fabricatedby forming a magnetic layer of a Co alloy, etc., a protective layer ofC—N, etc., and a lubricating layer of perfluoro-alkyl-polyether, etc.,in this order, directly on a non-magnetic substrate or via anon-magnetic underlayer which comprises at least one element selectedfrom the group consisting of Cr, Mo, W, Ta, V, Nb, Ta, Ti, Ge, Si, Coand Ni as a primary component, the above magnetic layer was formed bycontrolling film deposition conditions, such as substrate temperature,atmosphere and deposition rate, heat treatment conditions, compositionsof magnetic layer or under layer, a thickness of each layer,crystalline, the number of layers, etc. At a recording density of 3Gb/in² and at 10 kprm, these magnetic media were evaluated through theuse of a conventional magnetic head with the MR element as shown inFIGS. 11A and 11B on a conventional magnetic disk device as shown inFIGS. 10A and 10B. As a result, the present inventors found out that bygiving the above magnetic layer of a composition containing at least onemetal element selected from the group consisting of Co, Fe and Ni as aprimary component, and at least two elements selected from a secondgroup consisting of Cr, Mo, W, V, Nb, Ta, Ti, Zr, Hf, Pd, Pt, Rh, Ir andSi, it is possible to refine crystal grains and reduce the exchangeinteraction among crystal grains and also to reduce the absolute valueof normalized noise coefficient per recording density to not more than3×10⁻⁸ (μVrms)(inch)(μm)^(0.5)/(μVpp) even when recording and readingare performed at a transfer rate of not more than 20 MB/s ofconventional technology. This effect was remarkable especially duringlow-pressure, high-temperature and high-rate film depositions or duringfilm depositions at a high pressure and a low deposition rate. Underother conditions, however, this effect was good enough by optimizingcompositions and combinations.

[0017] On the other hand, in order to record at a high rate of not lessthan 50 MB/s, it was necessary to use an R/W-IC (Read and Write IC)which is capable of a high speed processing by puttingfine-pattern-width for not more than 0.35 μm to partial use at leastand, in addition, it was necessary to develop a magnetic recording headstructure capable of generating a strong magnetic recording field at ahigh rate in response to this fast driving current. In order to preventthe deterioration of fast signals, it is important that the IC beinstalled in a position as close to the head as possible and it wasdesirable to reduce the distance to not more than 2 cm. The presentinventors examined magnetic pole and head structures and materials formagnetic poles, and developed a magnetic head assembly with a totalinductance reduced to not more than 65 nH in which the magnetic corelength l₁ of a magnetic recording core composed of the lower magneticpole 118 and the upper magnetic pole 117 in FIG. 11A is not more than 35μm, and which is provided with a magnetic film with a resistivityexceeding 50 μΩcm or a multilayer film composed of a magnetic film andan insulating film in part of the magnetic poles composing the magneticcore, and which is mounted on a suspension 113 with an integratedconductive line through insulator 1116. Recording magnetic fieldsobtained by this magnetic head were evaluated with the aid of a magneticfield SEM, MFM, etc. As a result, the present inventors could ascertainthat a sufficient magnetic field can be generated even at a datatransfer rate of not less than 50 MB/s, and found out that recording ata transfer rate of not less than 50 MB/s is, in principle, possible.Materials for magnetic poles with a resistivity exceeding 50 μΩcminclude, for example, NiFe-base alloys, such as 42Ni-57Fe-1Cr,46Ni-52Fe-2Cr, 43Ni-56Fe-1Mo, 51Ni-47Fe-2S and 54Ni-43Fe-3P, andamorphous magnetic alloys, such as CoTaZr and CoNbZr. Examples ofmultilayer film composed of a magnetic film and an insulating filminclude a multilayer film composed of 89Fe-8Al-3Si and SiO₂ and amultilayer film composed of 8ONi-2OFe and ZrO₂.

[0018] When recording and reading on the above medium at 50 MB/s throughthe use of the magnetic head and circuit of the above construction,satisfactory recording was incapable due to a bad overwritecharacteristic, etc. and besides noise increased twice or three times.Thus, it became apparent that further ideas are necessary for ensuringrecording and reading both in high-density and high data transfer rate.Here, signals were read through the use of a conventional MR readelement with a narrow track width of 2 μm.

[0019] The reason for the above phenomenon was examined. The presentinventors considered that the above phenomenon is due to a bad frequencyresponse in the recording characteristic of the medium. Therefore, thecause was analyzed by performing a simulation through the use of a supercomputer, etc. and as a result, it became evident that there is aproblem in thermal fluctuations of magnetization and spin damping duringrecording process. Therefore, studies were carried out on mediumadditives capable of optimizing thermal fluctuations and dampingcoefficient. As a result, the present inventors found out that by addingat least one element selected from a third group consisting of La, Ce,Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Bi, Sb, Pb, Sn, Geand B to the composition of the above medium, it is possible to reducethe absolute value of normalized noise coefficient per recording densityto not more than 2.5×10⁻⁸ (μVrms) (inch)(μm)^(0.5)/(μVpp) even whenrecording is performed at 50 MB/s. This effect was observed when theabove elements were added in amounts of not less than 0.1 at %. However,their addition in an amount of 0.1 at % is sufficient. Addition inamounts of not more than 0.1 at % was undesirable because of aremarkable decrease in output. Furthermore, the effect was remarkablewhen rare earth elements were added. The above effect was alsoascertained in what is called a granular type medium in which anon-magnetic substance, such as SiO₂ and ZrO₂, and a magnetic materialwith a high crystalline anisotropy constant, such as CoPt and CoNiPt,were simultaneously formed by sputtering and the magnetic material witha high crystalline anisotropy constant was precipitated and dispersed byheat treatment at a temperature of about 300° C. to obtain the abovecomposition. Furthermore, in a case where the above magnetic layer ismade of an amorphous magnetic substance, the magnetic layer often hasperpendicular anisotropy. However, the same effect was also observed inthis case. Furthermore, in any of these instances, when the abovemagnetic layer was formed via a non-magnetic intermediate layercontaining at least one element selected from the group consisting ofCr, Mo, W, V, Nb, Ta, Zr, Hf, Ti, Ge, Si, Co, Ni, C and B as a primarycomponent, noise could be remarkably reduced because of statisticaladdition of signals and this was especially favorable for noisereduction. Furthermore, what is especially noteworthy is that byreducing the magnetic core length of the above magnetic head to not morethan 50 μm, a sharp and strong magnetic field could be generated withincreased efficiency and recording on a medium with a higher coerciveforce was possible. This is preferable because higher densities can beobtained. Furthermore, by installing the above R/W-IC near thesuspension, the rise time of a recording magnetic field could be madefurther shorter. This permitted sharp recording and enabled medium noiseto be relatively reduced. Therefore, this is more preferable.

[0020] In order to perform recording and reading at a high density ofnot less than 5 Gb/in², it was necessary to perform the reading ofmagnetic information through the use of a magnetic head having aneffective read-track width of not more than 0.9 μm with giantmagnetoresistive effect or tunneling-magnetoresistive effect, andperforms the reading of magnetic information at a high density of notless than 5 Gb/in². By performing reading like this, a signal-to-noiseratio of not less than 20 dB of the device necessary for the operationof the device was obtained with the aid of the signal processing methodand it was necessary to combine the magnetic head with signal processingsuch as EPRML or EEPRML, trellis coding, ECCs, etc. Incidentally, thegiant magnetoresistive element (GMR) and tunneling magnetic headtechnologies are disclosed in JP-A-61-097906, JP-A-02-61572,JP-A-04-35831, JP-A-07-333015, JP-A-02-148643 and JP-A-02-218904. Aneffective track width of not more than 0.9 μm was realized by puttinglithography technology based on an i-line stepper or a KrF stepper, FIBfabrication technology, etc. to full use.

[0021] The above system was a very epoch-making product as a magneticdisk. However, the present inventors found out that recording can beassisted by instantaneously heating a medium to the temperature range offrom about 50° C. to 250° C. with a magnetic disk provided with aheat-generating portion and thereby reducing the coercive force at ahigh frequency, and that this idea is further effective. In other words,in this system the load put on the recording portion and the materialfor recording magnetic poles could be reduced, and recording at a highdensity of not less than 5 Gb/in² and a high data transfer rate of notless than 50 MB/s was possible even with a recording track width of notmore than 0.9 μm and even when a magnetic pole material with asaturation magnetic flux density of 1 T was used. Thus, this wasespecially advantageous.

[0022] With respect to this effect, access time can also be shortened byperforming magnetic recording immediately after heat application to amagnetic recording medium and performing reading with the aid of theabove giant magnetoresistive element or element having atunneling-magnetoresistive effect. This is further preferable.

[0023] Furthermore, by using a semiconductor laser chip as the aboveheat-generating portion, an effective head volume can be reduced andhigh-speed positioning becomes possible. This is especially preferable.In addition, in order to shorten access time and ensure positioning witha higher accuracy, it is especially effective to position the head by arotary actuator method in at least two stages of coarse and finemovement adjustments.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024]FIG. 1 shows schematically the essential portion of a magneticrecording medium of the invention;

[0025]FIG. 2 shows schematically the essential portion of a magnetichead assembly of the invention;

[0026]FIG. 3A shows schematically a plan view of a magnetic recordingdevice of the invention;

[0027]FIG. 3B shows a cross-sectional view of the magnetic recordingdevice shown in FIG. 3A;

[0028]FIG. 4 shows schematically the essential portion of anothermagnetic head assembly of the invention;

[0029]FIG. 5A shows schematically the essential portion of a magnetichead of the invention;

[0030]FIG. 5B shows schematically the essential portion of anothermagnetic head of the invention;

[0031]FIG. 6A shows schematically the essential portion of magneticwrite head pole structure of the invention;

[0032]FIG. 6B shows a cross-sectional view of the magnetic head polestructure shown in FIG. 6A;

[0033]FIG. 7A shows schematically the essential portion of anothermagnetic write head pole structure of the invention;

[0034]FIG. 7B shows a cross-sectional view of the magnetic write headpole structure shown in FIG. 7A;

[0035]FIG. 8A shows schematically the essential portion of still anothermagnetic write head pole structure of the invention;

[0036]FIG. 8B shows a cross-sectional view of the magnetic write headpole structure shown in FIG. 8A;

[0037]FIG. 9 is a graph showing an effect of additive elements;

[0038]FIG. 10A shows schematically a plan view of a conventionalmagnetic disk device;

[0039]FIG. 10B shows a sectional view of the conventional magnetic diskdevice shown in FIG. 10A;

[0040]FIG. 11A shows schematically a partial sectional view of theessential portion of a conventional magnetic head with write and readelements;

[0041]FIG. 11B shows schematically the conventional magnetic head shownin FIG. 11A; and

[0042]FIG. 12 shows schematically the essential portion of aconventional magnetic recording medium.

EXAMPLE 1

[0043] The magnetic disk of the invention is shown in FIGS. 3A and 3B.FIG. 3A is a plan view of the device and FIG. 3B is a sectional view ofthe device. In the device of the invention, a recording medium 31 of theinvention, which will be described later in detail by referring to FIG.1, is fixed to a rotary hub 34 and rotated by a motor 310, and recordingis performed by a magnetic head 32, which will be described later indetail by referring to FIGS. 11A and 11B. The magnetic head 32 issupported by a rotary actuator 33 via an arm 311 and positioned fast andin a stable manner in a prescribed position of the rotating recordingmedium 31. In the drawing, the numeral 313 denotes a suspension. Asshown in FIG. 2 which illustrates the details of the suspension 313, thesuspension 313 used in this device is an integrated circuit suspensionin which the wiring 21 and an insulating layer are integrally formed ona plate spring through the use of the thin film technology so that theinductance of the wiring 21 is not more than 15 nH. Usual wiring oftwist wires and wiring with an inductance of not less than 15 nH,signals higher than 50 MB/s attenuate greatly. Thus, conventional typesof wiring could not been adequately put to practical use when circuitsof usual power were used. In a case where an R/W-IC portion 314 wasformed on the above integrated circuit suspension 313, in which thethin-film wiring and insulating layer were directly formed on the platespring, or an FPC for wiring, and the distance from the head was notmore than 2 cm, the attenuation of signals was not practically observedand an improvement in transfer rate of not less than tens of megabytesper second was observed compared to a case where an R/W-IC wasintegrated with a signal processing circuit and mounted on a circuitboard as conventionally. Thus, this was especially preferable. In thisexample of the invention, the distance was set at 1.5 and 1 cm.Incidentally, FIGS. 10A and 10B illustrates an example in which fourmagnetic disks 31-1 to 31-4 and eight magnetic heads 32 are mounted.However, at least one magnetic disk and at least one magnetic head maybe installed. In this example of the present invention, 1 to 30 headsand 1 to 15 magnetic disks were mounted on a casing 312 of magnetic diskdevice shown in FIG. 3.

[0044] The same prescribed electric circuit as conventional technologyis required for recording information, processing read signals andinputting/outputting information. In terms of power consumption,however, a circuit using a CMOS is advantageous in comparison with acircuit using a Bi-CMOS and it is necessary to downsize circuitry inorder to perform recording and reading at a high rate of 50 MB/s. In allcases, therefore, it was necessary to adopt the patterning process fornot more than 0.35 μm in fabricating a part of the R/W-IC. In an actualcase where a patterning process for not less than 0.5 μm was adopted,good recording could not be performed. Incidentally, for channel LSIsfor signal processing, etc., it is necessary to reduce the circuit scalein order to reduce power consumption and a patterning process for notmore than 0.25 μm was adopted. In this example, a signal processingcircuit in which waveform interference in the age of high-density designis positively utilized was introduced and separated from the aboveR/W-IC. This signal processing circuit is called MEEPRML (ModifiedEEPRML), in which EEPRML (Extended Extended Partial Response MaximumLikelihood) is enhanced and the ECC function is also enhanced.Furthermore, in the case of perpendicular magnetic recording, readingwas performed by the PR5 signal processing method, etc. These componentswere installed in the circuit board on the cover 312, etc. The number ofrevolutions of the device was 10,000 rpm and the flying height was from26 to 28 nm in all cases.

[0045] The medium and magnetic head of the present invention, whichcompose the magnetic recording and reading device of the presentinvention, is explained below in further detail.

[0046] First, the medium of the present invention is explained byreferring to FIG. 1. The numeral 11 indicates a non-magnetic substratewhich is made of glass, NiP-plated Al, ceramics, Si, plastics, etc. andformed on a disk with a diameter of, for example, 3.5″, 2.5″, 1.8″ and1″, a tape or a card. The numeral 12 indicates a non-magnetic underlayerwhich is made of Cr, Mo, W, CrMo, CrTi, CrCo, NiCr, CoCr, Ta, TiCr, C,Ge, TiNb, etc. and contains at least one kind of element selected fromthe group consisting of Cr, Mo, W, V, Nb, Ta, Ti, Ge, Si, Co and Ni as aprimary component. The numeral 13 indicates a hard magnetic layer whichcomprises a crystalline magnetic substance of CoCrPtLa, CoCrTaCe,CoNiPtPr, CoPtNd—SiO₂, FeNiCoCrPm, CoFePdTaSm, NiTaSiEu, CoWTaGd,CoNbVTb, GdFeCoPtTa, GdTbFeCoZrRh, FeRhSiBi—N, CoPtIrSn—CoO, etc., whichcrystalline magnetic substance contains at least one metal elementselected from the group consisting of Co, Fe and Ni as a primarycomponent, at least two elements selected from a second group consistingof Cr, Mo, W, V, Nb, Ta, Ti, Zr, Hf, Pd, Pt, Rh, Ir and Si, and a leastone kind of element selected from a third group consisting of La, Ce,Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Bi, Sb, Pb, Sn, Geand B. This hard magnetic material has an absolute value of normalizednoise coefficient per recording density of not more than 2.5×10⁻⁸(μVrms)(inch)(μm)^(0.5)/(μVpp). The numeral 14 indicates a protectivelayer made of C to which N and H are added in combination, H-added C,BN, ZrNbN, etc. The numeral 15 indicates a lubricant ofperfluoro-alkyl-polyether having adsorptive or reactive end-groups suchas OH and NH₂, an organic fatty acid, etc. Between the non-magneticunder layer 12 and the hard magnetic layer 13, there may be provided asecond non-magnetic underlayer whose composition is further adjusted andwhich has a lattice constant capable of being more easily matched tothat of the magnetic film. When the above magnetic layer is divided by anon-magnetic intermediate layer which contains at least one elementselected from the group consisting of Cr, Mo, W, V, Nb, Ta, Zr, Hf, Ti,Ge, Si, Co, Ni, C and B as a primary component, noise decreases almostin proportion to the square root of the total number of magnetic layers.Therefore, this is more preferable.

[0047] Embodiments of medium of the present invention are explainedbelow in further detail. The magnetic disks of the present inventionshown in Table 1 were obtained by first forming an underlayer on a glassdisk substrate with a diameter of 3.5, 2.5, 1.8 or 1 inch, then forminga magnetic layer of single-layer, two-layer or multilayer structure, a10-nm thick carbon protective film to which 10% N is added, and finallyforming a 5-nm thick lubricating film of perfluoro alkyl polyetherhaving —OH end group after surface treatment. The above underlayer ismade of the Cr alloys, Mo alloys, Ti alloys, W alloys, etc., whichcontains at least one element selected from the group consisting of Cr,Mo, W, V, Nb, Ta, Ti, Ge, Si, Co and Ni as a primary component. Theabove magnetic layer comprises a crystalline magnetic material ofCoCrPtGd, CoCrPtTaNd, CoPtDy—SiO₂, FeCoNiMoTaBi, NiFeCrPtGe, FeNiTaIrSm,etc., which crystalline magnetic material contains at least one metalelement selected from the group consisting of Co, Fe and Ni as a primarycomponent, at least two elements selected from a second group consistingof Cr, Mo, W, V, Nb, Ta, Ti, Zr, Hf, Pd, Pt, Rh, Ir and Si, and at leastone element selected from a third group consisting of La, Ce, Pr, Nd,Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Bi, Sb, Pb, Sn, Ge and B.

[0048] The above underlayer and magnetic layer were both formed by meansof a DC magnetron sputtering device and the above protective film wasformed in an N₂ gas atmosphere by the plasma-induced reactive magnetronsputtering method. Incidentally, in this example, parameters could bevaried independently of the underlayer and magnetic film each other andAr pressures of from 1 to 10 m Torr, substrate temperatures of from 100to 300° C. and deposition rates of from 0.1 to 1 nm/s were used. In theunderlayer, Cr, Ta, Nb, V, Si and Ge or alloys such as Co60Cr40,Mo90-Cr10, Ta90-Cr10, Ni5OCr50, Cr90-V10, Cr90-Ti10, Ti95-Cr5, Ti-Tal5,Ti-Nbl5, TiPd20, TiPt15, etc. were used as a single layer or two layerscomposed of dissimilar metal layers. Thus, samples of differentunderlayer compositions were prepared. The total film thickness of theunderlayer was from 10 to 100 nm, that of the magnetic layer was from 10to 100 nm, and that of the protective film was 10 nm. A multilayermedium 70 nm in thickness was also made by way of trial by depositingten layers of a combination of 5-nm thick CoCr₇Pt₆Gd₃ and 2-nm thick Ptlayers. The magnetic recording medium of the present invention wasevaluated by SEM or TEM and it was found that the magnetic layer ispredominantly composed of fine crystal grains with their average grainsizes of not more than 12 nm and not less than 8 nm for bothlongitudinal and perpendicular media. TABLE 1 Ar sput- Tempera- Undertering ture of Orientation layer pressure substrate of magnetic Magneticlayer (nm) (nm) (mTorr) (° C.) layer 1 CoCr₁₅Pt₈La₄ (25) CrTi 2 250in-plane (40) 2 CoMo₁₅Pt₈Ce₁ (25) CrTI 2 250 in-plane (60) 3 CoW₁₉Pt₄Pr₂(25) CrTi 2 250 in-plane (100) 4 CoCr₁₅Pt₈Ta₄Nd₄ (28) MoCr 5 100in-plane (10) 5 CoCr₁₆Pt₁₀Ta₃Pm₅ MoCr 5 150 in-plane (28) (20) 6CoCr₁₇Pt₁₀Ta₂Sm₃ MoCr 5 200 in-plane (28) (30) 7 CoCr₁₃Pt₈V₅Eu₄ (35) CrV10 300 in-plane (10) 8 CoCr₁₆Pt₁₂Nb₂Gd₆ Wsi 10 300 in-plane (35) (20) 9CoCr₁₅Pt₁₅V₄Tb₄ (35) CoCr 10 300 in-plane (30) 10 NiFe₁₀Cr₁₀Ir₄Dy₄ (26)NiCr 1 209 in-plane (20) 11 FeNi₃₀Ta₅Rh₄Ho₂ (18) MoCr 2 250 in-plane(30) 12 FeCr₁₉Pt₈Er₇ (29) CoCr 2 275 in-plane (50) 13 CoPt₂₀Ir₄Tm₁—SiO₂Ta (45) 1 250 in-plane (25) 14 CoPt₁₅Ni₄Yb₈—ZrO₂ V (30) 1 181 in-plane(25) 15 CoNi₂₂Pt₂₀Pd₄Lu_(0.5)— Nb (50) 1 224 in-plane SiO₂ (22) 16CoCr₂₃Pt₁₀Ti₅Bi₄ TiCr 2 174 perpendicu- (100) (50) lar 17CoCr₂₃Pt₁₀Ti₅Bi₄ TiCr 3 160 perpendicu- (100) (50) lar 18CoCr₂₁Pt₈Hf₃Sn₄ (60) TiTa 4 156 perpendicu- (50) lar 19 CoCr₂₂Pt₈Pd₃Ge₁₅(50) CoTaZr 6 140 perpendicu- (50) lar 20 CoCr₂₂Pt₆Rh₂B₀ ₁ (40) CoNbZr 6106 perpendicu- (50) lar 21 CoCr₂₂Pt₆si₂Sm₄ (40) TiPd 6 191 perpendicu-(50) lar 22 CoCr₇Pt₆Gd₃/Pt (70) SiN 5 151 perpendicu- (50) lar

[0049] Next, the magnetic head of the present invention is explained byreferring to FIG. 2 and FIG. 11A. A magnetic pole 117 of 43Ni-57Fe witha saturation magnetic flux density of 1.5 T and a resistivity of 50 μΩcmand another magnetic pole 118 of Ni8OFe2O with a saturation magneticflux density of 1.0 T and a resistivity of 28 μΩcm were formed by theframe plating method. Cu wiring of 2 layers and 15 turns was formedwithin a magnetic core length l₁ of 35 μm. The length of a record gap111 was 0.32 μm (material for the gap: Al₂O₃). Furthermore, the readelement was fabricated as follows. A magnetically free NiFe/Co film (6nm), a Cu film (2.5 nm), a magnetically fixed layer CoFe film (5 nm) anda CrMnPt film (25 nm) were first formed one after another and arectangular pattern was obtained. After that, a permanent magnet ofCo80-Ni15-Pt5 (15 nm)/Cr (12 nm) and an electrode film of Ta (120 mm)were arranged on both ends of the pattern and a giant magnetoresistiveelement with a track width of 0.9 μm, which is determined by the gapdistance between the electrodes, was provided on a 2-μm thick platedshielding film of Ni8O—Fe2O by the i-line lithography technology,thereby giving this structure to the read element (shield gap: 0.3 μm,material for the gap: Al₂O₃). The magnetic head element provided withthis read element was formed on a slider made of Al₂O₃—TiC with a sizeof 1.0×0.8×0.2 mm³. Incidentally, the recording track width was trimmedto 1.1 μm from the floating surface side by the FIB (Focused Ion Beam)fabrication technology and a shaped rail structure was fabricated to thefloating surface of the head. In addition, to improve the anti-adhesiveproperty minute projections were provided at three points of thefloating surface and a C/Si protective film with a total thickness of 3nm was formed on the floating surface. As shown in FIG. 3, this head,along with an RW-IC 314 for which the scaledown process for 0.35 μm inthis example was adopted, was fixed with an adhesive to an integratedcircuit suspension 313 of the present invention on which a conductiveline pattern through an insulating film were formed by the thin filmfabrication process. A magnetic head assembly was thus obtained. As aresult of the foregoing, in the integrated circuit suspension of thepresent invention for a disk with a diameter of 3.5, 2.5, 1.8 or 1 inch,the total inductance of the head assembly measured from R/W IC terminalsat 10 MHz was 65, 63, 61 and 57 nH, respectively, not more than 65 nH.

[0050] Incidentally, heads with a magnetic core length 11 of 25, 30 and40 μm were also made by changing the number of turns to 9, 11 and 13,respectively. When the magnetic core length was 40 μm, in the integratedcircuit suspension of the present invention for a disk with a diameterof 3.5, 2.5, 1.8 or 1 inch, the total inductance was as large as 75, 73,71 and 68 nH, respectively. In these cases, the overwrite characteristicat 50 MB/s was as low as 20 dB, sufficiently sharp recording could notbe performed, and noise was very large. Thus, these heads could not beput to practical use. From the above, it became apparent that it isnecessary that the magnetic core length be not more than 35 μm and thatthe total inductance be not more than 65 nH. Table 1 shows only cases inwhich goods results were obtained with an overwrite characteristic ofnot less than 30 dB. Furthermore, when the characteristic was evaluatedon a tunneling magnetic head with a read track width of 0.85 μm, made bythe technology stated in JP-A-02-148643 and JP-A-02-218904, quite thesame result was obtained. With a conventional MR head having the sametrack width for comparison, however, even in a case where the conditionof the device was evaluated through the use of a signal processingcircuit of the EEPRML type by the lithography process of 0.25 μm,sufficient read output and error rates could not be obtained. Thus, thisconventional MR head could not bear the evaluation.

[0051] The device characteristics of the present invention are describedblow. A signal processing circuit of the EEPRML type by the lithographyprocess of 0.25 μm was used. In order to perform high-density, high datarate recording with high quality and a high signal-to-noise ratio forthe characteristic in each record track position, it is necessary toensure a strong and sharp recording magnetic field at a high frequencyand, at the same time, it is necessary to reduce the irregularity of thesaw tooth magnetic domains at record bit boundaries by reducing thecrystalline grainsize in the medium and also reducing the exchangeinteraction among magnetic crystalline grains, to reduce the noise atbit boundaries that increases in proportion to recording density, and toensure an appropriate response to a high-frequency magnetic field byoptimizing the damping of magnetization during recording. Forcomparison, media were made without the addition of only the third groupof elements so that these media correspond to those given in Table 1. Onthe media of these comparative examples, when recording was performed ata transfer rate of not less than 20 MB/s, the absolute value ofnormalized noise coefficient per recording density increased abruptly at5 Gb/in² even when the above-mentioned head and R/W-IC were used. Whenrecording was performed at 50 MB/s, the absolute value of normalizednoise coefficient per recording density reached large values of from 10to 30×10⁻⁸ (μVrms)(inch)(m)^(0.5)/(μVpp) and the bit error rate of thedevice was worse than 10⁻⁵. Thus, these medium could not be used forpractical use. In contrast, all the media of the embodiments shown inTable 1 had an absolute value of normalized noise coefficient perrecording density of from 1 to 2.5×10⁻⁸ (μVrms)(inch)(μm)^(0.5)/(μVpp),which are not more than 2.5×10⁻⁸ (μVrms)(inch)(μm)^(0.5)/(μVpp), and thebit error rate was better than 10⁻⁹ even under the conditions of both 5Gb/in² and 50 MB/s. Thus, it became apparent that these media of thisexample were especially preferable.

[0052] For the effect of the elements of third group to a medium, caseswith additives of from 0.1 to 15% were described in this example.However, as is apparent from FIG. 9 which shows cases with varied Lacontents of 0.01, 0.1, 0.5, 1, 2, 10, 15, and 20 at % under theconditions of #1 of Example 1, the signal-to-noise ratio in recording at50 MB/s improved remarkably. The effect is sufficient when the quantityof additives is 1 at %. The output and signal-to-noise ratio decreasedremarkably when the quantity of additives was not less than 15 at % and,therefore, this was not preferable. Furthermore, the effect wasespecially remarkable when rare earth elements were added.

[0053] A medium of another embodiment was prepared under the sameconditions as those for the above first embodiment of Example 1 bydividing the magnetic layer into two layers by a non-magneticintermediate layer, which contains as a main element at least oneselected from the group consisting of Cr, Mo, W, V, Nb, Ta, Zr, Hf, Ti,Ge, Si, Co, Ni, C and B singly or Cr-Ti10, Mo-Cr10, W-Si5, Ta-Si5,Nb-Zr10, Ta-Cr5, Zr-Hf10, Hf-Ti5, Ti-Si10, Ge-Pt5, Si-Ru11, Co-Cr30,C-N10, B-N10, etc. However, noise reduced to approximately 70% and thedevice operated adequately even under the conditions of both 7 Gb/in²and 50 MB/s. Thus, the effect was more remarkable. It is needless to saythat the above effect does not depend on the diameter of a disk or formsof medium such as a disk, tape and card.

EXAMPLE 2

[0054] Another example of the present invention is explained byreferring to the conceptual drawing of a magnetic head assembly shown inFIG. 4. For a magnetic head 42, first as recording elements,40Ni-55Fe-5Cr with a saturation magnetic flux density of 1.4 T and aresistivity of 60 μΩcm was used as the material for a magnetic pole 117with a track width of 0.6 μm and another magnetic pole 118 was formedfrom CoTaZr with a resistivity of 120 μΩcm in FIG. 11A. Track widthfabrication was performed by trimming on the basis of the FIB technologyas with Example 1. A record gap length of 0.25 μm (material for the gap:Al₂O₃-3%SiO₂) was selected, the magnetic core length l₁ was 30 μm, andan Al coil 116 of 2 layers and 12 turns was used. Furthermore, the readelement was fabricated as follows. A magnetically free NiFe/Co film (6nm), a CuNi film (2.5 nm), a magnetically fixed layer of CoFe/Ru/CoFefilm (6 nm) and an MnIr film (15 nm) were first formed one after anotherand a rectangular pattern was fabricated. After that, a permanent magnetof Co75-Cr15-Pt12 (10 nm)/CrTi (5 nm) and an electrode film of Nb (100mm) were arranged on both ends of the pattern and the above giantmagnetoresistive element with a track width of 0.5 μm, which isdetermined by the distance between the electrodes, was provided on a2.5-μm thick plated shielding layer of Ni8O-Fe2O through an 0.45 μmthick shield gap 110 in FIG. 11A of Al₂O₃, thereby giving this structureto the read element (total shield gap: 0.20 μm, material for the gap:ZrO₂). A magnetic head 42 was obtained by forming this element on aslider made of Al₂O₃-TiC with a size of 1.0×0.8×0.2 mm³. The magnetichead assembly was obtained by mounting this head on an integratedcircuit suspension of the present invention of FIG. 4 in which leadpattern through an insulating layer were formed by the thin filmfabrication process.

[0055] In FIG. 4, with the assistance of a fine adjustment portion 43 ofelectromagnetic drive, etc. capable of position corrections of about 10μm at a high rate, a suspension 44 has the function of positioning amagnetic head 42 in the prescribed position of the recording medium at ahigh speed in collaboration with the rough movement function of a rotaryair actuator 45. For this reason, in Example 2, the R/W-IC of thisexample fabricated by the processes for 0.35 and 0.25 μm line widths wasmounted on a wiring FPC (Flexible Printed Circuit) installed adjacent toan integrated circuit suspension in which lead pattern was formed by thethin film process, and its distance from the head was 3, 2, 1.5, 1 and0.7 cm. Incidentally, a signal processing LSI of the EEPRML by thescaledown process for 0.25 μm was used. Incidentally, the fineadjustment portion 43 is not limited to a fine movement means of theelectromagnetic force drive type and may be a fine movement means of thepiezoelectric force drive type, magnetostrictive force drive type, etc.As a result of a comparison and examination, it was found that the typein which a multilayer piezoelectric device is used has the least adverseeffect on power consumption and the read element of GMR or MR. However,the other types also met required functions. Another disk device of thepresent invention was obtained by mounting this head assembly on amagnetic disk device of the present invention shown in FIGS. 3A and 3Band by using the media of 2.5″ and 1.8″ diameters shown in Table 1 andthe same circuit as in Example 1. In Example 2, combinations of 1 to 10media and 1 to 20 heads were used. Incidentally, a slider of shaped railstructure with three minute projections was used and a 3-nm thickprotective film of C—N—H was provided on the bearing surface. However,during the evaluation, the flying height of the magnetic head was 25 nmand the number of revolutions was 15,000 and 25,000 rpm.

[0056] In all the combinations, the device operated adequately in acondition better than a bit error rate of 10⁻⁹ under the conditions of10 Gb/in² and 50 MB/s. Thus, this effect was more remarkable. At 20,000rpm, recording was severer and the device operated in a condition betterthan a bit error rate of 10⁻¹⁰ when the R/W-IC of the present inventionbased on the process for a line width of 0.25 μm was used. This wasespecially preferable. Incidentally, for the distance between the R/W-ICof the present invention and the head of the present invention, the datatransfer rate could be increased to 50, 54, 54, 54 and 55 MB/S withdecreasing distance to 3, 2, 1.5, 1 and 0.7 cm, respectively. Distancesof not more than 2cm were especially effective. It is needless to saythat this effect does not depend on the diameter of a disk or forms ofmedium such as a disk, tape and card.

EXAMPLE 3

[0057] A third example of the present invention is described below byreferring to FIGS. SA and 5B, FIGS. 8A and 8B and FIGS. 3A and 3B.

[0058] As shown in FIGS. 5A and 5B, a laser chip 52, 52′ of about 0.3 mmsquare was mounted on a position-correcting mount 51, 51′ of thepiezoelectric force type, electromagnetic force type or magnetostrictiveforce type. The laser chip thus mounted on the position-correcting mountwas then mounted on a head slider 50, 50′ as shown in FIGS. 5A and 5B topermit adjustments so that a recording and reading element portion 53,53′ and a laser beam position 54, 54′ are located almost on the samerecord track 55, 55′. An Al₂O₃-TiC slider of shaped rail structure witha size of 0.7×0.2 mm³ (FIG. 5A), provided with three minute projections,was used and a 3-nm thick protective film of C-N was provided on thefloating surface. The volume including the laser chip (FIG. SB) was1.0×0.9×0.2 mm³, and the distance over which corrections are possiblewas 20 μm maximum. Although the correction mechanism is not alwaysnecessary, the absence of this mechanism was not much preferable becauseof a low margin for reproducibility. Incidentally, the laser wavelengthwas 830, 780, 650 and 630 nm and the power was from 5 to 50 mW. Toprevent degradation, the end faces of the laser were provided withprotective films. The shape of a laser beam was almost oval as indicatedby 54, 54′. As shown in this figure, an examination was made as to twocases. In one case, the direction of the minor axis of about 1 μm wasalmost parallel to the record track 55, 55′ and in the other case, thedirection of the minor axis was perpendicular to the record track 55,55′. The flying height was 10 nm.

[0059] Incidentally, the recording element shown in FIGS. 6A and 6B,FIGS. 7A and 7B and FIGS. 8A and 8B was first used corresponding to therecording element 53, 53′. In the embodiment shown in FIGS. 6A and 6B, a36Ni-62Fe-2Nb film with a resistivity of 75 μΩcm and a film thickness of1.8 μm was formed as 62 and 64 and a 45Ni-55Fe film with a resistivityof 45 μΩcm and a film thickness of 1.8 μm was formed as 61 and 63. Asshown in FIG. 6A, a track width T_(ww) of 0.53 μm was obtained in thewafer state by performing trimming through the use of ion milling, theRIE method, etc. Furthermore, a magnetic core length l₁ of 35 μm, amagnetic pole length l₂ of 50, 55, 60 or 65 μm, a number of turns of Cucoil of 15, and a recording gap length Gl of 0.19 μm (material for thegap: Al₂O₃-5%SiO₂) were obtained.

[0060] In another embodiment shown in FIGS. 7A and 7B, an80Co-10Ni-10Fe-1P film with a resistivity of 20 μΩcm and a filmthickness of 0.7 μm was formed as 72 and 74 and a 75Co-10Ni-10Fe-5P filmwith a resistivity of 65 μΩcm and a film thickness of 1.5 μm was formedas 71 and 73. As shown in FIG. 7A, a track width T_(ww) of 0.47 μm wasobtained in the wafer state by performing fabrication and, furthermore,a magnetic core length l₁ of 33 μm, a magnetic pole length l₂ of 45, 50,55, 60 or 65 μm, a number of turns of Cu coil 116 of 15, and a recordgap length Gl of 0.18 μm (material for the gap: Al₂O₃-5%SiO₂) wereobtained.

[0061] In a further embodiment shown in FIGS. 8A and 8B, a multilayerfilm, obtained by alternately depositing an 90Fe-5Al-5Si film with aresistivity of 20 μΩcm and a film thickness of 0.1 μm and a 10-nm thickZrO₂ layer to form a total of ten layers, was formed as 82 and a75Co-15Ta-10Zr film with a resistivity of 100 μΩcm and a film thicknessof 1.5 μm was formed as 118. As shown in FIG. 8A, a track width T_(ww)of 0.5 μm was obtained in the wafer state by performing trimming by theFIB method and, furthermore, a 44Ni-56Fe film with a resistivity of 45cm and a film thickness of 1.9 μm was formed with an end width of 0.7μm. The magnetic core length 11 was 33 μm, the magnetic pole length l₂was 40, 50, 55, 60 or 65 μm, the number of turns of Cu coil 116 was 11,and the record gap length Gl was 0.20 μm (material for the gap:Al₂O₃-7%SiO₂). Incidentally, still further embodiments with the samemagnetic core length, but with different magnetic pole lengths of 55, 60and 65 μm were also fabricated in addition to the above embodiments.

[0062] In all of these embodiments, the read element was fabricated asfollows. A magnetically free NiFe/CoFe film (5 nm), a CuNi film (2.5nm), a magnetically fixed layer of CoFe/Ru/CoFe film (5 nm) and an MnIr(13 nm) film were formed one after another and a rectangular pattern wasobtained. After that, a permanent magnet of Co75-Ni15-Pt10-5%HfO₂ (12nm) and an electrode film of Nb—Tl (90 mm) were arranged on both ends ofthe pattern and a giant magnetoresistive element with a track width of0.41 μm, which is determined by the spacing between electrodes, wasprovided on a 2.1-μm thick plated shielding film of Ni80-Fe20 throughthe gap, thereby giving this structure to the read element (total shieldgap: 0.8 μm, material for the gap: Ta₂O₅). The read portion thusfabricated was used as the magnetic head element of the presentinvention. In this example, an RW-IC fabricated by the scaledown processfor 0.25 μm was mounted on the integrated circuit suspension thatsupports the above head. A signal processing LSI separately installedwas of the EEPRM type formed by the scaledown processes for 0.25 and 0.2μm.

[0063] The following media of the same structure as those shown in FIG.1 were newly fabricated in addition to the media shown in Table 1. Anamorphous magnetic material, which contains at least one metal elementselected from the group consisting of Co, Fe and Ni as a primarycomponent, at least two elements selected from a second group consistingof Cr, Mo, W, V, Nb, Ta, Ti, Zr, Hf, Pd, Pt, Rh, Ir and Si, and a leastone element selected from a third group consisting of La, Ce, Pr, Nd,Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Bi, Sb, Pb, Sn, Ge and B,was formed on a non-magnetic substrate of Si with a diameter of 3.5,2.5, 1.8, 1 inch, etc. The numeral 14 indicates a protective film madeof N-added C, H-added C, BN, ZrNbN, AlN, SiAlOH, etc. The numeral 15indicates a lubricant of perfluoro-alkyl-polyether having adsorptive orreactive end groups such as OH and NH₂, an organic fatty acid, etc.Between the non-magnetic underlayer 12 and the hard magnetic layer 13,there may be provided a second non-magnetic underlayer whose compositionis further adjusted. When the above magnetic layer is divided by anon-magnetic intermediate layer, which contains as a main element atleast one selected from the group consisting of Cr, Mo, V, Nb, Ta, Zr,Hf, Ti, Ge, Si, Co, Ni, Al, Zn, C and B singly or Cr—Ti10, Mo—Cr10,W—S15, Ta—Si5, Nb—Zr10, Ta—Cr5, Zr—Hf10, Hf—Ti5, Ti—Si10, Ge—Pt5,Si—Ru11, Co—Cr30, C—N10, B—N10, etc., noise decreases almost inproportion to the square root of the total number of magnetic.Therefore, this is more preferable.

[0064] This example is explained below in further detail. A magneticdisk was fabricated by forming a non-magnetic underlayer of SiN, Cralloy, etc. on an Si disk with a diameter of 1.8″ and then furtherdepositing one after another an amorphous magnetic layer of TbFeCo,DyFeCo, NdTbFeCo, TbFeCoNb, TbFeCoPt, etc., an 8-nm thick protectivefilm of carbon to which 15% N is added, and a 5-nm thick lubricatingfilm of perfluoro-alkyl-polyether having end groups of —OH.

[0065] Both the underlayer of SiN, Cr alloy, etc. and the magnetic layerwere formed by means of an RF magnetron sputtering device using Ar gasand the protective film was further formed in an N₂ gas atmosphere bythe plasma-induced reactive magnetron sputtering method. On thatoccasion, the Ar pressures was from 0.5 to 10 m Torr, the substratetemperatures was from 50 to 200° C., and the deposition rate was about 3nm/s. In the underlayer, Al₂O₃ and Cr—Ti were used as a single layer ortwo layers composed of dissimilar underlayers in addition to SiN and CrThus, samples of different underlayer compositions were prepared. Thetotal film thickness of the underlayer was from 10 to 200 nm, that ofthe amorphous magnetic layer of TbFeCo, DyFeCo, NdTbFeCo, TbFeCoNb,TbFeCoPt, TbFeCoBi, etc. was from 20 to 750 nm, and that of theprotective film was 8 nm. Compositions with a higher Fe concentrationthan usual compositions used in magneto-optic disks permit greatsaturation magnetization and allow the film thickness of a medium to berelatively reduced. Therefore, this was favorable in terms of magneticrecording. Magnetic disks of the present invention made by way of trialin Example 3 are shown in Table 2. TABLE 2 Ar sput- Tempera- Undertering ture of Orientation layer pressure substrate of magnetic Magneticlayer (nm) (nm) (mTorr) (° C.) layer 1 CoTb₁₀Zr₃Pt₁₅ (200) CrTi (40) 0.2200 in-plane 2 FeCo₁₀Tb₁₅Pt₅Cr₂ (270) CrTa (60) 0.2 180 perpendicular 3FeCo₅Tb₂₀Si₅Pd₂ (350) Al₂O₃ (100) 0.5 150 perpendicular 4FeCo₅Tb—Bi₅Ta₂Cr₁ (20) CrV (30) 0.5 100 perpendicular 5 FeCo₁₀Tb₁₅Nb₅Mo₂(270) Cr (20) 1.0 150 perpendicular 6 FeCo₁₅Dy₁₅Bi₅V₂Ti₂ (450) ZnS (30)1.0 200 perpendicular 7 FeCo₁₀Tb₃₀Ge₅Zr₂Ir₂ (570) Wti (10) 2.0 50perpendicular 8 FeCo₁₀Nd₁₅Pt₂W₂ (370) MoSi (20) 2.0 200 perpendicular 9FeCo₅Dy₁₀Lo₅Rh₂Hf₂ (45) NiCr (30) 5.0 50 perpendicular 10FeCo₁₃Tb₂6Ce₅Pt₂Tr₂ (350) CoCr (20) 5.0 100 perpendicular 11FeCo₁₀Tb₁₅Pt₂Ta₂ (270) TaCr (30) 0.2 150 perpendicular 12 FeCo₇Dy₂₅Nd₅(350) MoCr (90) 0.2 175 perpendicular 13 FeCo₃₆Tb₁₆Nd₁₃Pt₂V₃ (650) TaCr(65) 0.5 150 perpendicular 14 FeCo₄₂Nd₂₀Pr₅Pt₂Ti₂ (750) V (40) 0.5 181perpendicular 15 FeCo₁₆Tb₂₆Eu₅Pt₄Pd₂ (750) Nb (40) 1.0 124 perpendicular16 FeCo₁₃Tb₂₃Nb₁W₂ (650) TiCr (50) 1.0 54 perpendicular 17FeCo₁₀Tb₂₀Pm₃Si₂W₂ (590) WCr (50) 2.0 165 perpendicular 18FeCo₁₅Dy₁₅Gd₅Ir₂W₂ (580) TiTa (60) 2.0 65 perpendicular 19FeCo₁₅Tb₂₂Rh₂Zr₂ (570) TiV (50) 5.0 145 perpendicular 20FeCo₁₀Nd₁₅Pd₂Si₂ (690) TiPt (50) 5.0 116 perpendicular 21FeCo₁₂Tb₂₈Iio₅Ir₂Ti₂ TiPd (50) 10 195 perpendicular (680) 22FeCo₁₀Tb₂₂Er₅Zr₂V₂ (530) TiNb (60) 10 121 perpendicular 23FeCo₁₀Tb₂₂Tm₅Nb₂Mo₂ (570) SiN (60) 10 101 perpendicular 24FeCo₁₀Tb₂₂Yb₅Cr₂W₂ (480) C (50) 1.0 95 perpendicular 25 FeCo₁₀Tb₂₂Lu₅(500) Ge (50) 1.0 81 perpendicular

[0066] In all of the media of this example, the magnetic films are madeof amorphous materials with an in-plane or a perpendicular anisotropy.Especially, in perpendicular media, the noise coefficient is generallynegative. In media with a coercive squareness of not less than 0.95,noise was especially low and this was preferable. In all cases, theabsolute value of normalized noise coefficient per recording density wasnot more than 2.5×10⁻⁸ (μVrms)(inch)(μm)^(0.5)/(μVpp). Under the sameconditions as with the above third example in Table 2, media of anotherembodiment were fabricated by dividing the magnetic layer into twolayers by a non-magnetic intermediate layer, which is made of Cr, Mo, W,V, Nb, Ta, Zr, Hf, Ti, Ge, Si, Co, Ni, C or B singly or Cr—Ti10,Mo—Cr10, W—Si5, Ta—Si5, Nb—Zr10, Ta—Cr5, Zr—Hf10, Hf—Ti5, Ti—Si10,Ge—Pt5, Si—Ru11, Co—Cr30, C—N10, B—N10, S—N50, etc. In all these media,noise decreased to the levels of from 65 to 75%. This was especiallypreferable.

[0067] To fabricate a magnetic disk device, 10 media shown in Table 1 orTable 2 were mounted as 31 and 20 heads of each of the above embodimentswere mounted as shown in FIGS. 3A and 3B. Recording was performed bymagnetic fields from the magnetic heads while controlling the coerciveforce of media by the local heating effected by means of a laser duringinformation recording. The number of revolutions was from 20,000 to30,000 rpm and temperature rises in the recording positions of media bylocal heating were optimally controlled in the range of about 50° C. to300° C. Under this method, recording conditions are susceptible tofluctuations in external temperature. Therefore, it was desired tooptimize laser power by performing trial writing in the initial stage ofrecording and at prescribed intervals of time after operation.

[0068] In all the media, when the major axis of laser almost coincidedwith the track direction, interference with adjoining tracks was smalland the best characteristics were obtained. Even in a case where theminor axis coincided with the track direction, however, high densitiesabout twice the density in conventional technology could be realized.More specifically, areal densities of not less than 7 Gb/in² could beachieved at 50 MB/s for the media of the embodiments shown in Table 1and areal densities of not less than 15 Gb/in² could be achieved at 50MB/s similarly for the media of the embodiments shown in Table 2. In adevice provided with the above media having a magnetic layer dividedinto two layers, recording density could be improved by about 20%. Thiswas especially preferable. Incidentally, a read signal processing LSIfabricated by the process for 0.2 μm was about 30% favorable in terms ofpower consumption and processing speed.

EXAMPLE 4

[0069] The heads of Example 3 were also adopted as the magnetic heads ofExample 1 and Example 2 and evaluated. In all of these heads of Example3, operation of the device at areal densities of not less than 7 Gb/in²and data transfer rates of not less than 60 MB/s were verified andcharacteristics equal to or better than those obtained in Example 1 andExample 2 were obtained. This was especially preferable in terms of datatransfer rate. When the magnetic pole length was 55, 60, and 65 μm,recording and reading were possible at a data transfer rate of from 60to 65 MB/s. However, when the magnetic pole length was not more than 50μm, data transfer rate of from 66 to 70 MB/s was possible. This wasespecially preferable. It was ascertained by a computer simulation thatit is important to reduce not only the magnetic core length l₁, but alsothe magnetic pole length l₂ because eddy currents are generated in therear part of a magnetic pole. The R/W-IC portion was separated from thesignal processing portion and formed by the scaledown process for notless than 0.35 μm. After that, this R/W-IC portion was mounted on theintegrated circuit suspension of the present invention in whichthin-film lead layer and an insulating layer are formed directly on aplate spring by the thin film process, or on a wiring FPC, and thedistance from the head was set at not more than 1 cm. In this case,degradation of signals was not practically observed and an improvementin data transfer rate of not less than 50 MB/s was observed compared toa case in which an R/W-IC was integrated with a signal processingcircuit and installed on a circuit board as conventionally. This wasespecially preferable.

[0070] The above Examples 1 to 4 represent typical inventions disclosedin the present invention and examples that can be easily analogized bythose skilled in the art also included in the scope of the presentinvention. Similar effects are obtained from the RF magnetron sputteringmethod, ECR sputtering method and helicon sputtering method, forexample. Furthermore, similar effects are obtained form theoblique-evaporation method in an oxygen atmosphere and the ionizedcluster beam method and also by changing the incidence positioncorresponding to each radius of a disk. It is needless to say thatsimilar effects are obtained by installing a Peltier-effect element inthe head and performing heating. Furthermore, the magnetic recordingmedium, head and device disclosed in this invention enable magneticrecording and reading in high data transfer rate at not less than 50MB/s to be performed at a recording density of not less than 5 Gb/in².Therefore, high data transfer rate and large-capacity magnetic recordingand reading devices in which magnetic tapes, magnetic cards,magneto-optic disks, etc., are used as the magnetic recording media ofthe present invention, are also included in the scope of the presentinvention.

[0071] As mentioned above, the use of the magnetic recording medium andmagnetic recording and reading device of the present invention, for thefirst time, enables high data transfer rate and large-capacity recordingand reading to be performed. As a result, magnetic recording and readingdevices with very strong product competitiveness can be realized.

What is claimed is:
 1. A magnetic recording and reading device having atransfer rate of not less than 50 MB/s comprising: a magnetic recordingmedium having an absolute value of normalized noise coefficient perrecording density of not more than 2.5×10⁻⁸(μVrms)(inch)(μm)^(0.5)/(μVpp); a magnetic head which is mounted on anintegrated circuit suspension so that a total inductance is reduced tobe not more than 65 nH and having a magnetic core which is not more than35 μm of length, a part of the magnetic core being formed by a magneticfilm having a resistivity exceeding at least 50 μΩcm or by a multilayerfilm consisting of a magnetic film and an insulating film; and a fastR/W-IC having a line width of not more than 0.35 μm which is installedin a position within 2 cm from a rear end of said magnetic head; whereinsaid magnetic head is provided with a reading element including a giantmagnetoresistance effect element or a thin film havingtunneling-magnetoresistance effect, with an effective track width of notmore than 0.9 μm, and performs reading of magnetic information at anareal density of not less than 5 Gb/in², and wherein said magneticrecording medium comprises (a) a magnetic layer containing at least onemetal element selected from the group consisting of Co, Fe and Ni as aprimary component, and at least two elements selected from a secondgroup consisting of Cr, Mo, W, V, Nb, Ta, Ti, Zr, Hf, Pd, Pt, Rh, Ir andSi, and at least one element selected from a third group consisting La,Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Bi, Sb, Pb, Sn,Ge and B, and (b) a non-magnetic layer containing at least one kind ofelement selected from the group consisting of Cr, Mo, W, V, Nb, Ta, Zr,Hf, Ti, Ge, Si, Co, Ni, C, B, Pt, Ru and N.
 2. A magnetic recording andreading device according to claim 1, wherein said magnetic head has amagnetic pole length of not more than 50 μm.
 3. A magnetic recording andreading device according to claim 1, wherein said magnetic layer of saidmagnetic medium is an amorphous material.